Written by Jane Smith · Reviewed by Alex Chen · July 30, 2026
Two-way converter between Arabic numbers and Roman numerals.
Roman numerals are the number system that refuses to retire. This converter translates between ordinary numbers and their Roman spellings in both directions: type 1994 and read MCMXCIV, or paste MCMXCIV and read 1994. The rules are strict, the notation is compact, and the page applies the same conventions historians, clockmakers, and film studios still use.
The entire system rests on seven letters. I stands for one, V for five, X for ten, L for fifty, C for one hundred, D for five hundred, and M for one thousand. The letters carry mnemonics that have survived for centuries: I resembles a single stroke, V looks like the open hand it counts, X crosses the arms, C opens the Latin word centum for a hundred, and M opens mille for a thousand. Every Roman number on the page is built from these seven symbols and nothing else.
Type a number in either box and press the matching direction. The Number to Roman field accepts any whole number from 1 to 3999, and the Roman field accepts the letters I, V, X, L, C, D, and M in any valid arrangement. The converter checks the input before translating, so a value outside the range or a letter that is not part of the system is rejected with a message instead of producing a nonsense result.
Enter 1994 in the Number to Roman box and the converter returns MCMXCIV. The construction is easier to follow than it looks. Start with M for one thousand, leaving 994. Since 900 is written as CM, the hundred that precedes one thousand, take CM and 94 remains. Ninety is XC, the ten that precedes one hundred, leaving 4. Four is IV, the one that precedes five. Read left to right the parts are M, CM, XC, and IV, giving MCMXCIV with no symbol repeated more than three times.
The round trip works in reverse. Paste MCMXCIV into the Roman field and the converter returns 1994, summing one thousand, nine hundred, ninety, and four by their positions.
Roman numerals avoid writing four identical symbols in a row. Instead of IIII for four, the system places a smaller value before a larger one and subtracts: IV means five minus one. The same convention covers 9 as IX, 40 as XL, 90 as XC, 400 as CD, and 900 as CM. Only one small letter may precede a larger one, which is why 1994 is written MCMXCIV rather than MCMXIIII. The converter applies this rule automatically when building an answer and expects it when reading one, so the numbers it produces match the classical spelling rather than a padded variant.
Years are the most common place Roman numerals survive. Try a few on the page: 2024 becomes MMXXIV, 2026 is MMXXVI, and 1900 becomes MCM. Super Bowl numbering, copyright lines, book front matter, and the closing credits of films all favor the style, and clock faces keep the tradition on every wall. Because years rarely exceed 3999, the converter's range covers every year you are likely to encounter.
Because the classical system has no symbol for five thousand or ten thousand. Numbers above 3999 would need either an extended notation with bars over letters or repeated thousands, and the page keeps to the standard range that has a single accepted spelling.
The converter validates the input by re-encoding the value it reads. If the letters do not follow the rules, such as a repeated V or an impossible order like IL for 49, the page flags the entry instead of returning a guessed number.
Because the subtractive rule forbids four identical symbols. Placing I before V signals five minus one, and the same logic builds every number from 4 up to the threshold of the next symbol.
The converter works with uppercase forms, and the output is always capitalized. If you enter lowercase letters, the tool treats the case as unimportant and reads the symbols by their letter value.
3999, written MMMCMXCIX. Every whole number from 1 up to that ceiling converts cleanly, and anything beyond it falls outside the classical alphabet.
The system has outlived every empire that used it. Roman numerals mark the chapters of textbooks, the acts of plays, the volumes of encyclopedias, and the crowns of monarchs who share a name. They survive on watch faces, cornerstone dates, and the year markers of older buildings, and they remain the standard for the Super Bowl. Converting between them and ordinary numbers is a small, exact job, and this page does it in either direction without sending your input anywhere.
The numerals come from the Latin alphabet of ancient Rome, where tallies carved on wood or stone used strokes for small numbers and borrowed letters for larger ones. The system survived the empire by centuries, serving merchants, scholars, and bureaucrats through the Middle Ages and into the Renaissance before the digits we use today took over for arithmetic.
What survives now is ceremonial and decorative. Monarchs and popes take a numeral as a title, film sequels wear one in their credits, and clock faces still print hours in the old style. Because the characters are familiar but rarely written by hand, a converter in both directions stays genuinely useful for dates, outlines, and anything that needs a classic look.